An Iraqi firefighter hoses down a burned bus after a car bomb attack in Kirkuk, 290 kilometers (180 miles) north of Baghdad, Iraq, Thursday, Feb. 23, 2012. A rapid series of attacks spread over a wide swath of Iraqi territory killed and injured dozens of Iraqis on Thursday, targeting mostly security forces.

Photo: Emad Matti, Associated Press

An Iraqi firefighter hoses down a burned bus after a car bomb...

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An Iraqi policeman inspects a destroyed vehicle at the site of a blast in the northern city of Kirkuk on February 23, 2012. A wave of bombings and shootings across Iraq killed more than 30 people and wounded dozens more, security officials said.

Photo: Marwan Ibrahim, AFP/Getty Images

An Iraqi policeman inspects a destroyed vehicle at the site of a...

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An Iraqi girl inspects damages following a blast in the Kadhimiyah district in north Baghdad on February 23, 2012. A wave of bombings and shootings killed at least 38 people and wounded more than 250, Iraq's deadliest day in more than a month, security and medical officials said.

Photo: Ali Al-saadi, AFP/Getty Images

An Iraqi girl inspects damages following a blast in the Kadhimiyah...

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An Iraqi policeman inspects the debris of a vehicle following a blast in Baquba, the provincial capital of the Diyala province, on February 23, 2012. A wave of bombings and shootings killed at least 38 people and wounded more than 250, Iraq's deadliest day in more than a month, security and medical officials said.

Photo: Str, AFP/Getty Images

An Iraqi policeman inspects the debris of a vehicle following a...

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An Iraqi firefighter douses a car as security forces inspect the site of a blast in the northern city of Kirkuk on February 23, 2012. A wave of bombings and shootings across Iraq killed more than 30 people and wounded dozens more, security officials said.

Photo: Marwan Ibrahim, AFP/Getty Images

An Iraqi firefighter douses a car as security forces inspect the...

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Iraqi firefighters try to extinguish a burning bus at the scene of a car bomb explosion in Baghdad, Iraq, Thursday, Feb. 23, 2012. Iraqi officials say a string of morning attacks across Baghdad has killed and injured dozens of Iraqis.

Bombs and deadly shootings relentlessly pounded Iraqis on Thursday, killing at least 55 people and wounding more than 225 in a widespread wave of violence the government called a "frantic attempt" by insurgents to prove the country will never be stable.

Cars burned, school desks were bloodied, bandaged victims lay in hospitals and pools of blood were left with the wounded on floors of bombed businesses after the daylong series of attacks in 12 cities across Iraq.

The assault demonstrated how vulnerable the country remains two months after the U.S. military left and put the onus for protecting the public solely in the hands of Iraqi forces.

Primary school blasted

"There was no reason for this bomb. A primary school is here, students came to study and people came to work," Karim Abbas woefully said in the town of Musayyib, where he saw a car bomb parked near an elementary school kill three people and wound 73. Most of the injured in the town, about 40 miles south of Baghdad, were schoolchildren.

Other Iraqis, fed up with the continued violence, furiously blamed security forces for letting it happen.

"We want to know: What were the thousands of policemen and soldiers in Baghdad doing today while the terrorists were roaming the city and spreading violence?" said Ahmed al-Tamimi, who was working at an Education Ministry office a block away from a restaurant bombed in the Shiite neighborhood of Kazimiyah in northern Baghdad.

He described a hellish scene of human flesh and pools of blood at the restaurant, where another car bomb killed nine people and wounded 19.

No group immediately claimed responsibility for the latest attacks, but car bombs are a hallmark of al Qaeda. The Iraqi Interior Ministry blamed al Qaeda insurgents for the violence.

Security forces targeted

"These attacks are part of frantic attempts by the terrorist groups to show that the security situation in Iraq will not ever be stable," the ministry said in a statement. "These attacks are part of al Qaeda efforts to deliver a message to its supporters that al Qaeda is still operating inside Iraq, and it has the ability to launch strikes inside the capital or other cities and towns."

Fifteen of the day's 26 attacks targeted security forces on patrols, at checkpoints and around government and political offices. Six policemen were killed at their checkpoint in northern Baghdad in a pre-dawn drive-by shooting. A suicide bomber blew up his car in front of a police station in Baquba, 35 miles northeast of Baghdad, killing two and wounding eight.

Public confidence eroded

Such violence undermines the public's confidence in the ability of their policemen and soldiers to protect everyday citizens, and discourages people from joining or helping the security forces.

The violence now is nowhere as frequent as it was during the tit-for-tat sectarian fighting that almost pushed Iraq into civil war a few years ago. But the attacks appear to be more deadly than they were before American military's withdrawal in late December.

Days after the American military left, a Dec. 22 wave of bombs targeting Shiites killed at least 69 people. That happened twice more over the following three weeks, killing 78 and 53, respectively. Al Qaeda was blamed for them all.

The renewed potency of the violence points to a dangerous security gap that Iraqi forces have not yet solved without the help of the U.S. military: Gathering intelligence on militants plotting attacks.